Are medically unexplained symptoms and functional disorders predictive for the illness course? A two-year follow-up on patients' health and health care utilisation.

Objective: To investigate whether the general practitioners' (GP) diagnosis of medically unexplained symptoms (MUS) and/or the diagnosis functional disorders (FD) can predict the patients' 2-year outcome in relation to physical and mental health and health care utilisation. Furthermore, to identify relevant clinical factors which may help the GP predict the patient's outcome.

Method: The study included 38 GPs and 1785 consecutive patients who presented a new health problem. The GPs completed a questionnaire on diagnosis for each patient. Patients completed the Common Mental Disorder Questionnaire (CMDQ) and the SF-36 questionnaire at baseline and after 24 months. A stratified sample of 701 patients was diagnosed with a psychiatric research interview. Data on health cost was obtained from national registers.

Results: A FD diagnosis following the research interview was associated with a decline in physical health (OR 3.27(95%CI 1.84-5.81)), but this was not the case with MUS diagnosed by the GP. MUS was associated with a poor outcome on mental health (OR 2.16 (95%CI 1.07-4.31)). More than 4 symptoms were associated with a poor outcome on physical health (OR 5.35 (95%CI 2.28-12.56)) and on mental health (OR 2.17(95%CI 1.02-4.59)). Neither FD nor MUS were associated with higher total health care use. However, FD (OR 2.31(95%CI 1.24-4.31)) and MUS (OR 1.98(95%CI 1.04-3.75)) was associated with increased cost in primary care.

Conclusion: Our current diagnoses of MUS show limitations in their prediction of the patients' illness course. Although, the ICD-10 diagnoses of functional disorders was not developed for the primary care setting, our results indicate that some of its elements would be useful to bring in when rethinking the diagnosis for MUS in primary care, elements that are easily obtainable for the GP in a normal consultation. Our results may contribute to the construction of a more useful diagnostic for these patients in primary care.